I have a simple docker-compose file like the following:

version: "3.7"
services: 
  mongo:
    image: asia.gcr.io/myproj/mymongo:latest
    hostname: mongo
    volumes: 
      - type: bind
        source: $MONGO_DB_DATA
        target: /data/db
    command: [ "--bind_ip_all", "--replSet", "rs0", "--wiredTigerCacheSizeGB", "1.5"]

I am launching it in Kubernetes using the following command

docker-compose config | docker stack deploy    --orchestrator kubernetes --compose-file - mystack

However, when the pod fails with this error

Failed to pull image "asia.gcr.io/myproj/mymongo:latest": rpc error: code = Unknown desc = Error response from daemon: unauthorized: You don't have the needed permissions to perform this operation, and you may have invalid credentials. To authenticate your request, follow the steps in: https://cloud.google.com/container-registry/docs/advanced-authentication

My private registry is the gcloud one. I have already logged in docker like the following using the service account keyfile.

docker login  -u _json_key -p "$(cat keyfile.json)" https://asia.gcr.io

The image is pulled correctly when I run

docker-compose pull

From this link https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/, I found that I need to create ImagePullSecrets

I have two questions.

1. How can I write the ImagePullSecrets syntax in my docker-compose so that it is referred correctly.

2. The method that the links mentions asks you to use .docker/config.json file. However, my config.json has

   "auths": { "asia.gcr.io": {}, }, It doesn't include the username and password since I configured it using the keyfile. How can I do this?

3. Or is there any simpler way to do this?